Lecture 15. A. Radiation Review
Constant Speed of Light -- no matter wavelength or freq! TRAIN EX:
-- cars' length is like wavelength, how often they pass is freq.
Doppler shifts move up/down in freq (or wavelength)
- more shift for higher radial velocity of object
- less shift for less radial velocity of object
- (AMOUNT of shift)/(original freq.) = (radial velocity)/(speed of light c)
Behavior vs. Wavelength
- -- energy/intensity -- 2 ways to get energy from light:
- more ENERGETIC radiation: a photon of higher f (or shorter
, or bluer color)
has more energy than one of lower f
- MORE radiation: but energy from MANY more WEAKER photons can add up to
more than energy from fewer strong photons
- -- penetrating power
- energetic photons -- X-rays, gammas, etc. -- can penetrate flesh, and more
- NOT MUCH visible light cannot penetrate opaque objects -- but SOME can
- if visible light cannot penetrate an object,
same number of less energetic photons cannot either
- given many more photons however, more manage to penetrate
- refraction -- longer the wavelength, less the refraction
-- amount that light bends in lenses, water droplets in rainbows
- diffraction -- longer the wavelength, greater the diffraction (FYI)
- diffraction is how light "bends" around objects
-- hills, buildings, trees, etc.
- why KGLT uses radio waves, not visible